BugLink: https://bugs.launchpad.net/bugs/1820063

The hv_kvp_daemon service requires the hv_kvp device and should
be started when the device appears and stopped in it disappears.
Solution is based off the one provided at
https://bugzilla.redhat.com/show_bug.cgi?id=1195029#c22.
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
Acked-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Kleber Souza <kleber.souza@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>